From ball screws to butterflies, valves are some of the hardest working and most reliable members of the process control and automation community. And just like those other components, many types of valves have been getting some serious technical makeovers in recent years—to the point that users often don't know about the helpful skills they've acquired.
However, some users are well aware of recent innovations in several primary valve technologies because they rely on them every day. For instance, Ineos Chlor is a major European producer of chlor-alkali and chlorine derivatives, and it recently reduced process variability by 5% at its plant in Runcorn, U.K., by replacing four traditional butterfly valves with Fisher Control-Disk valves from Emerson Process Management. This reduced variability, enabled the plant to increase throughput, avoid several unplanned shutdowns that could have cost a total of $600,000, and achieve a 96% overall equipment effectiveness (OEE) rating for the unit where the valves were installed (Figure 1).
"For a plant this size, even a modest reduction in variability can have a significant payback," explains Barry Makepeace, Ineos Chlor's control and instrumentation engineer. "Applying the Control-Disk valve not only saved us money, but also enabled us to optimize process control without sacrificing flow capacity or needing to re-pipe."
Runcorn previously used its butterfly valves to control the temperature and flow of cooling water to its primary condensers. Tight control is essential because if the condensers' temperature is too low, there will be residual chlorine in the system, which has to be removed. If the temperature is too high, there's an increased risk of a safety trip or plant shutdown. Each trip and subsequent unplanned shutdown can cost up to $100,000.
Unfortunately, the older valves had a small control range and a large dead band, which reduced their response to temperature changes. In the 12 months before replacing its valves, the plant experienced 23 trips and big production losses. However, adopting the Control-Disk valves provided a control range of 15 to 70% of travel, approaching the range of a segmented ball valve. This tighter, more reliable valve control enabled Runcorn's operators to optimize temperature set points and avoid at least six unplanned shutdowns.
Tank Farm Retrofit in Turkey
One of the most useful ways that recent valve innovations can be applied is in helping older systems gain a new lease on life. For example, the Tupras Izmit refinery in Kocael province, Turkey, recently undertook a major modernization program that included retrofitting more than 900 valves at the refinery's tank farms with Rotork's valve actuators and two-wire digital controls (Figure 2). Located near the Sea of Marmara, the 53-year-old refinery is the largest of four refineries operated by the Turkish Petroleum Refineries Co., and it produces more than 11 million tons of LPG, naphtha, gasoline, jet fuel, kerosene and diesel fuel annually.
Besides the retrofit, Tupras was also expanding and building new refinery facilities on an adjacent site with help from Técnicas Reunidas, an EPC contractor based in Madrid, Spain. This part of the overall project required more than 400 of Rotork's IQ electric actuators.